Every Scumskull is constructed from black or white pixels on a 5x5
grid. Additionally there are certain constraints on the shape of a
Scumskull.

A Scumskull must be symmetric to the vertical axis.

A Scumskull must be contiguous. That is, all black pixels have
to be connected. Diagonal connections are allowed.

A Scumskull must be expletive. That is, the bounding box of the
black pixels of a Scumskull must cover the whole 5x5 grid. Or, there
must be at least one black pixel on the leftmost and rightmost columns
and the topmost and bottommost rows of the grid.

An exhaustive search showed that according to this definition
there are 12,209 possible Scumskulls.

Learn more about the Scumskullz
formations,
crowd behaviour and tactics of attacking other invaders. Scumskullz
appear as various moving formations, tactical offence and defence
arrangements or misguide their enemies with deception.